No, never myself. Maybe the previous owner did.I am using an Ortofon OM 305 cartridge. Want to buy an Ortofon OM 30 as soon as I fix the problem. It gives off hum even when the cartridge is disconnected.
Not sure about continuity of the tonearm wiring and AC line input. (Let me ask you: why AC? Isn't it operated by DC?)
On weekends I will borrow my friend's multimeter and check the turntable from A to Z.
I was also give a suggestion to purchase a noise filter. Could that be helpful?